Sunderland captain John O'Shea is happy for Santiago Vergini over recent form.
The Argie is impressing in a central defensive role.
O'Shea told the Sunderland Echo: "It's just a confidence factor.
"You go back to players who came in at Manchester United years ago, whether it be from France or South America.
"Some of them took a season to get used to it.
"I know the football is intense in South America, but I don't think it compares over 90 minutes to the Premier League.
"It was a case of us getting to know Santi and him getting to know us, and the manager getting his points across over how we would adapt to everything.
"He went to right-back and did fantastic towards the end of last season and at the start of this season.
"He deserved a call-up to the not-so-easy (Argentina) squad to get into!
"That just shows you how well he's done and the progression he keeps making."
